Online Hydration Calculator – GymBeam Blog

The online hydration calculator will help you find out how much fluid you should consume on average each day. Adequate hydration is very important because all processes in the body take place in water. Did you know that water makes up approximately 60% of body weight in the average adult?

Simply put, no one can do without water. Adequate intake has a positive effect not only on health, but also on sports performance. Calculate how many litres of fluid you should consume per day.

How to Use the Online Hydration Calculator?

1. Enter your gender and body weight in the form.*
2. Click the “Calculate” button.
3. The calculator will then calculate the interval of daily recommended fluid intake in litres.

*If you are significantly overweight or obese, do not calculate with your current weight. The recommended fluid intake would then be too high. Calculate what your weight would be at a BMI of 24 and use this adjusted value. For example, our online BMI calculator can help you with the calculation.

During the day, a person loses an average of around 1.5–3 l of fluids, if we take into account water losses through normal sweating, urine, stool, breathing and skin. This amount, plus some extra for the proper functioning of the body, then needs to be replenished. Our calculator will help you find out what volume of fluid this is.

But beware, the hydration calculation will only give you an indicative result. The amount may not exactly correspond to what your body actually needs. A number of other factors come into play that cannot be taken into account by calculation. ^[2]

What Affects the Daily Need for Fluids?

• Temperature and humidity of the environment
• Amount and intensity of physical activity
• Diet composition (for example, a higher intake of fibre or salt increases the need for water)
• Consumption of caffeine and alcohol
• Pregnancy and breastfeeding
• Health condition (e.g., some diseases increase fluid loss) ^[2]

All these factors can further increase the need for fluids. In addition, it may vary slightly from day to day, so today may be different from tomorrow. In general, however, it is ideal to consume at least the amount that the calculator has calculated as the lower limit.

How to Recognise Adequate Hydration of the Body?

If you are not sure whether you are sufficiently hydrated, a simple test will help you, namely, estimating hydration according to urine colour. If it is light to clear, you are getting enough fluids. If, on the other hand, it is darker, you are at risk of dehydration and you need to increase your fluid intake.

You can easily monitor yourself over time, compare the colour with the following scale and adjust the amount of fluids you take in accordingly.

What Makes up the Daily Fluid Intake?

Have you calculated your daily fluid intake, and the result seems too high? Do you feel like you can’t possibly drink that much? Don’t worry, the recommended fluid intake is not the amount you have to take in just in drinks.

• Approximately 20–30% of the total fluid requirement is made up of fluids from food. So, if your daily requirement is 2,000 ml, you practically eat 400–600 ml of it in the form of vegetables, fruits, dairy products, cooked cereals, and so on.
• Another approximately 10% is created by the body itself as part of nutrient metabolism (carbohydrates, proteins and fats).
• When you need 2,000 ml, only 1,200–1,400 ml remains to be drunk. ^[1,2]

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What Fluids to Drink?

As you probably already suspect, a proper drinking regimen should be based on pure water. You can also supplement it with mineral waters or unsweetened tea as needed and according to your tastes.

Ideally, take sweetened beverages, juices, or diet drinks only as an occasional supplement to please your taste buds.

Does Coffee Count towards the Drinking Regime?

Whether we can count our morning cup of coffee towards our total drinking regime is a question that never gets old. We ask it over and over again because it is known that caffeine has a diuretic effect (promotes urine excretion). But fortunately, this is nothing you need to worry about if you don’t consume too much caffeine per day.

A daily dose of caffeine up to 400 mg, which is also considered the upper safe limit for health according to EFSA (European Food Safety Authority) for an average 70 kg person, has no negative effect on hydration. In practice, this corresponds to approximately 4–5 cups of coffee (espresso, cappuccino, etc.). You can safely count your regular daily cups of coffee towards your drinking regimen. ^[3]

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How Does the Drinking Regimen of Athletes Differ?

Athletes generally have a higher need for fluids to avoid dehydration. However, those who engage in endurance sports often also need to replenish electrolytes during prolonged sporting activity. These are minerals such as sodium, chlorides, potassium, calcium and magnesium, which are lost from the body through sweating.

All these micronutrients have a number of key functions in the body. They are involved in hydration, muscle activity, nerve transmission and nutrient metabolism, and can thus fundamentally affect sports performance. Therefore, if the training lasts for more than an hour or you exercise in high temperature or humidity, it is also advisable to reach for isotonic drinks containing electrolytes during such exercise.

How to Use the Calculator in Practice?

Our hydration calculator will provide you with a great starting point. But remember that this is an indicative figure. Your own body is your best guide.

Key Points for Proper Hydration:

• Use the result from the calculator as the lower limit of your daily intake.
• Monitor the colour of your urine. It should ideally be light yellow. If it darkens, it’s time to drink.
• Drink continuously throughout the day, do not wait for the feeling of thirst.
• Increase your fluid intake during sports, in hot weather, with higher fibre intake, or if you are breastfeeding.